source: trunk/libs/newlib/src/newlib/libc/machine/cris/memmove.c @ 444

Last change on this file since 444 was 444, checked in by satin@…, 6 years ago

add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc
File size: 7.5 KB
Line 
1/* A memmove for CRIS.
2   Copyright (C) 2000-2005 Axis Communications.
3   All rights reserved.
4
5   Redistribution and use in source and binary forms, with or without
6   modification, are permitted provided that the following conditions
7   are met:
8
9   1. Redistributions of source code must retain the above copyright
10      notice, this list of conditions and the following disclaimer.
11
12   2. Neither the name of Axis Communications nor the names of its
13      contributors may be used to endorse or promote products derived
14      from this software without specific prior written permission.
15
16   THIS SOFTWARE IS PROVIDED BY AXIS COMMUNICATIONS AND ITS CONTRIBUTORS
17   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL AXIS
20   COMMUNICATIONS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
21   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
23   SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
25   STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
26   IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27   POSSIBILITY OF SUCH DAMAGE.  */
28
29/* FIXME: This file should really only be used for reference, as the
30   result is somewhat depending on gcc generating what we expect rather
31   than what we describe.  An assembly file should be used instead.
32
33   Even worse, we base it on memcpy, on the assumption that overlapping
34   moves are rare, and we will do no worse than the generic memmove.  */
35
36#include <stddef.h>
37
38/* Break even between movem and move16 is really at 38.7 * 2, but
39   modulo 44, so up to the next multiple of 44, we use ordinary code.  */
40#define MEMMOVE_BY_BLOCK_THRESHOLD (44 * 2)
41
42/* No name ambiguities in this file.  */
43__asm__ (".syntax no_register_prefix");
44
45void *
46memmove(void *pdst, const void *psrc, size_t pn)
47{
48  /* Now we want the parameters put in special registers.
49     Make sure the compiler is able to make something useful of this.
50     As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
51
52     If gcc was allright, it really would need no temporaries, and no
53     stack space to save stuff on.  */
54
55  register void *return_dst __asm__ ("r10") = pdst;
56  register unsigned char *dst __asm__ ("r13") = pdst;
57  register unsigned const char *src __asm__ ("r11") = psrc;
58  register int n __asm__ ("r12") = pn;
59
60  /* Check and handle overlap.  */
61  if (src < dst && dst < src + n)
62    {
63      /* Destructive overlap.  We could optimize this, but we don't (for
64         the moment).  */
65      src += n;
66      dst += n;
67      while (n--)
68        {
69          *--dst = *--src;
70        }
71
72      return return_dst;
73    }
74  /* Whew, no overlap.  Proceed as with memcpy.  We could call it instead
75     of having a copy here.  That would spoil some of the optimization, so
76     we take the trouble with having two copies.  */
77
78  /* When src is aligned but not dst, this makes a few extra needless
79     cycles.  I believe it would take as many to check that the
80     re-alignment was unnecessary.  */
81  if (((unsigned long) dst & 3) != 0
82      /* Don't align if we wouldn't copy more than a few bytes; so we
83         don't have to check further for overflows.  */
84      && n >= 3)
85  {
86    if ((unsigned long) dst & 1)
87      {
88        n--;
89        *dst = *src;
90        src++;
91        dst++;
92      }
93
94    if ((unsigned long) dst & 2)
95      {
96        n -= 2;
97        *(short *) dst = *(short *) src;
98        src += 2;
99        dst += 2;
100      }
101  }
102
103  /* Decide which copying method to use.  */
104  if (n >= MEMMOVE_BY_BLOCK_THRESHOLD)
105    {
106      /* It is not optimal to tell the compiler about clobbering any
107         registers; that will move the saving/restoring of those registers
108         to the function prologue/epilogue, and make non-movem sizes
109         suboptimal.  */
110      __asm__ volatile
111        ("\
112         ;; GCC does promise correct register allocations, but let's    \n\
113         ;; make sure it keeps its promises.                            \n\
114         .ifnc %0-%1-%2,$r13-$r11-$r12                                  \n\
115         .error \"GCC reg alloc bug: %0-%1-%4 != $r13-$r12-$r11\"       \n\
116         .endif                                                         \n\
117                                                                        \n\
118         ;; Save the registers we'll use in the movem process           \n\
119         ;; on the stack.                                               \n\
120         subq   11*4,sp                                                 \n\
121         movem  r10,[sp]                                                \n\
122                                                                        \n\
123         ;; Now we've got this:                                         \n\
124         ;; r11 - src                                                   \n\
125         ;; r13 - dst                                                   \n\
126         ;; r12 - n                                                     \n\
127                                                                        \n\
128         ;; Update n for the first loop.                                \n\
129         subq    44,r12                                                 \n\
1300:                                                                      \n\
131"
132#ifdef __arch_common_v10_v32
133         /* Cater to branch offset difference between v32 and v10.  We
134            assume the branch below has an 8-bit offset.  */
135"        setf\n"
136#endif
137"        movem  [r11+],r10                                              \n\
138         subq   44,r12                                                  \n\
139         bge     0b                                                     \n\
140         movem  r10,[r13+]                                              \n\
141                                                                        \n\
142         ;; Compensate for last loop underflowing n.                    \n\
143         addq   44,r12                                                  \n\
144                                                                        \n\
145         ;; Restore registers from stack.                               \n\
146         movem [sp+],r10"
147
148         /* Outputs.  */
149         : "=r" (dst), "=r" (src), "=r" (n)
150
151         /* Inputs.  */
152         : "0" (dst), "1" (src), "2" (n));
153    }
154
155  while (n >= 16)
156    {
157      *(long *) dst = *(long *) src; dst += 4; src += 4;
158      *(long *) dst = *(long *) src; dst += 4; src += 4;
159      *(long *) dst = *(long *) src; dst += 4; src += 4;
160      *(long *) dst = *(long *) src; dst += 4; src += 4;
161
162      n -= 16;
163    }
164
165  switch (n)
166    {
167    case 0:
168      break;
169
170    case 1:
171      *dst = *src;
172      break;
173
174    case 2:
175      *(short *) dst = *(short *) src;
176      break;
177
178    case 3:
179      *(short *) dst = *(short *) src; dst += 2; src += 2;
180      *dst = *src;
181      break;
182
183    case 4:
184      *(long *) dst = *(long *) src;
185      break;
186
187    case 5:
188      *(long *) dst = *(long *) src; dst += 4; src += 4;
189      *dst = *src;
190      break;
191
192    case 6:
193      *(long *) dst = *(long *) src; dst += 4; src += 4;
194      *(short *) dst = *(short *) src;
195      break;
196
197    case 7:
198      *(long *) dst = *(long *) src; dst += 4; src += 4;
199      *(short *) dst = *(short *) src; dst += 2; src += 2;
200      *dst = *src;
201      break;
202
203    case 8:
204      *(long *) dst = *(long *) src; dst += 4; src += 4;
205      *(long *) dst = *(long *) src;
206      break;
207
208    case 9:
209      *(long *) dst = *(long *) src; dst += 4; src += 4;
210      *(long *) dst = *(long *) src; dst += 4; src += 4;
211      *dst = *src;
212      break;
213
214    case 10:
215      *(long *) dst = *(long *) src; dst += 4; src += 4;
216      *(long *) dst = *(long *) src; dst += 4; src += 4;
217      *(short *) dst = *(short *) src;
218      break;
219
220    case 11:
221      *(long *) dst = *(long *) src; dst += 4; src += 4;
222      *(long *) dst = *(long *) src; dst += 4; src += 4;
223      *(short *) dst = *(short *) src; dst += 2; src += 2;
224      *dst = *src;
225      break;
226
227    case 12:
228      *(long *) dst = *(long *) src; dst += 4; src += 4;
229      *(long *) dst = *(long *) src; dst += 4; src += 4;
230      *(long *) dst = *(long *) src;
231      break;
232
233    case 13:
234      *(long *) dst = *(long *) src; dst += 4; src += 4;
235      *(long *) dst = *(long *) src; dst += 4; src += 4;
236      *(long *) dst = *(long *) src; dst += 4; src += 4;
237      *dst = *src;
238      break;
239
240    case 14:
241      *(long *) dst = *(long *) src; dst += 4; src += 4;
242      *(long *) dst = *(long *) src; dst += 4; src += 4;
243      *(long *) dst = *(long *) src; dst += 4; src += 4;
244      *(short *) dst = *(short *) src;
245      break;
246
247    case 15:
248      *(long *) dst = *(long *) src; dst += 4; src += 4;
249      *(long *) dst = *(long *) src; dst += 4; src += 4;
250      *(long *) dst = *(long *) src; dst += 4; src += 4;
251      *(short *) dst = *(short *) src; dst += 2; src += 2;
252      *dst = *src;
253      break;
254    }
255
256  return return_dst;
257}
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